Cell Phase
The first stage of the game, the Cell Phase, starts you with a generic single-celled organism that's representative of its entire species. This phase focuses on the basics of guiding your creature to find food and avoid becoming food. Through successive generations you can add more specialized parts to the creature. After a set number of generations, your creature evolves for life on land and the game moves to the next stage.
Creature Phase
The Creature Phase plays similarly to the Cell Phase but adds a few important mechanics. You again control a single individual of the species you're developing and attempt to find food and mates while avoiding being eaten or starving. This phase also allows you to determine how social your species is. You can choose between attempting to ally with other creatures, ignoring them, or attempting to kill and eat them. After a set number of generations, the game moves to the Tribal Phase.
Tribal Phase
The Tribal Phase represents a significant shift in game play. Instead of focusing on a single member of the species, you now control an entire tribe of that species. A fairly traditional real-time strategy interface allows you to give individual members or the entire tribe specific tasks. You must choose between attempting to ally with other tribes or conquer them in battle. After allying or defeating a set number of tribes, the game moves to the Civilization Phase.
Civilization Phase
The Civilization Phase builds on the Tribal Phase. Again you take control of a group of your species, this time an entire city. The goal of this stage is to take control of neighboring cities. You can take control by spreading your city's religion, military siege or by buying the city outright.
Space Phase
The final stage of the game, the Space Phase, focuses on exploration and trade with other races. Definitely the most open ended stage, this phase allows you to trade, socialize and war with other space-faring civilizations. You can also explore a huge number of solar systems and planets.